Structure of an oil-free compressor on a vehicle

ABSTRACT

An arrangement of an oil-free compressor apparatus on a rail vehicle for supplying compressed air to pneumatic units assigned to the rail vehicle. The arrangement includes an oil-free compressor and a cooler unit connected with the compressor. The arrangement also includes a rail vehicle having a floor with at least one opening. The compressor is fastened on at least one side to the vehicle floor such that a main axis of rotation of the compressor is arranged essentially vertical with respect to the vehicle floor. The cooler unit interacts with the at least one opening that is configured to take in cooling air to cool the compressor.

[0001] The invention relates to an arrangement of an oil-free compressor on a vehicle, particularly on a rail vehicle, for supplying compressed air to various pneumatic units assigned to the vehicle.

[0002] Normally, a pneumatic system is provided in the case of a rail vehicle, by means of which predominantly the brakes of the rail vehicle, as essential pneumatic units, are operated. For supplying the compressed air, a compressor is used in this case which is usually arranged on the outside of the rail vehicle and in the area of the vehicle floor along the length in a horizontally hanging or standing manner. The compressor consists of a driving unit, which generates a rotating movement and is normally constructed as an electric motor, and of a compressor unit, which essentially consists of several pot-type cylinders for interior pistons, which are arranged on a housing for a crankshaft, the crankshaft driven by way of the driving unit converting its rotating movement by way of one connecting rod respectively into a linear movement for each assigned piston for compressing taken-in air. In addition to this compressor unit constructed as a piston compressor, screw-type compressors are also generally known which are also included within the scope of the present invention. Furthermore, compressor units of this type may have a one-stage or multi-stage construction with at least one low-pressure stage and one high-pressure stage.

[0003] The compressors used in the vehicle field are normally subjected to a long continuous operation or to a frequent switching-on and switching-off, which, as a result of friction, leads to a high heat development. Therefore, in the past, compressors were predominantly used in the vehicle field which ensured a sufficient cooling effect on the basis of an oil lubrication. However, the oil lubrication carries the risk that the lubricating oil situated in the housing of the compressor unit, in the case of the piston compressor, penetrates by way of the piston-cylinder pairing into the pneumatic system, which may result in a fouling by oil of pneumatically operated brake units on the vehicle. Furthermore, the condensate, which occurs during the required air drying of the pneumatic system, because of its oil content, has to be collected for environmental protection reasons in heatable containers and has to be drained and disposed off at regular intervals. This leads to increased maintenance and disposal expenditures as well as to a high oil consumption. Added to the above are difficulties with emulsion formations in the oil circuit of these oil-lubricated compressor units which frequently occur in the case of a low switch-on duration in the winter operation.

[0004] Recently, dry-running compressors have therefore been increasingly used. A dry-running compressor operates in its compressor unit without a lubricating oil situated in the housing, that is, oil-free. Instead, in the case of a piston compressor, the lubrication on the piston travel path is replaced by a particularly low-friction dynamic sealing arrangement. All rotating components are normally disposed in roller bearings. The encapsulated roller bearings are provided with a temperature-stable long-lived grease filling. In the valve area, slidably guided components are largely avoided. Because of these measures, an oil lubrication will not be required in the compressor unit. The risk of a foiling by oil of the generated compressed air can therefore be excluded. As a result of the elimination of an oil circuit, the oil-free compressor can, in addition, have a relatively light construction.

[0005] Because of the light-construction trend, which is increasing in the vehicle field, light carrier structures are increasingly used also for frame constructions, which carrier structures, however, frequently have a number of unfavorable natural frequencies, which are close to the rotational speed of the compressor of the pneumatic system which is arranged thereon. It therefore presents considerable problems to sufficiently observe the required specifications concerning permissible structure-born noise levels.

[0006] It is an object of the present invention to improve the arrangement of an oil-free compressor on the vehicle such that the structure-borne noise level generated by the operation of the compressor is minimal.

[0007] Based on a piston compressor according to the preamble of claim 1, the object is achieved in connection with its characterizing features. The dependent claims which follow indicate advantageous further developments of the invention.

[0008] The invention includes the technical teaching that the main rotational axis of the compressor is to be arranged in an essentially vertical manner with respect to the vehicle floor, the compressor being fastened at least on its front side to the vehicle floor.

[0009] The principal advantage of the solution according to the invention is the fact that, as a result, a particularly low-vibration arrangement of the compressor on the vehicle is achieved. Various tests have shown that an essentially vertical axis of rotation of the compressor with respect to the vehicle floor; that is, an axis arranged in the range of from 0° to 10° with respect to the vertical line—no longer generates any noticeable vibration levels on the vehicle floor.

[0010] This phenomenon can be explained in that no forces and torques act in the direction of the axis of rotation of the compressor. However, these act to a significant extent vertically to the axis of rotation and thus parallel with respect to the vehicle floor. Forces and torques acting parallel to the vehicle floor again generate no noticeable vibration levels therein, because the vehicle floor has a rigid behavior with respect to such an alternating thrust stress. An axis of rotation of the compressor which is vertical with respect to the vehicle floor can be implemented only by means of an oil-free compressor because, in the case of an oil-lubricated compressor, a horizontal arrangement is necessary for constructional reasons in order to achieve a sufficient lubrication and, to this extent, a sufficient stability. When a piston compressor is used, the oil-free compressor according to the invention can be connected with the vehicle floor at such a level at which neither inertia forces and torques, nor gas forces act vertically with respect to the vehicle floor. Thus, it can be prevented, for example, in the case of built-in engines or built-in motor units, that vibrations originating from the compressor are unpleasantly felt at the driver's seat.

[0011] The compressor is preferably arranged standing on the vehicle floor in the interior of the vehicle and, adjacent to the vehicle floor, has a cooler unit on the face side which, by way of at least one opening in the vehicle floor leading to the outside takes in air for cooling the compressor. By means of this special arrangement in the interior of the vehicle, little floor surface of the vehicle is needed, which permits a considerable saving of space with respect to the limited floor surface. Furthermore, the compressor is thereby housed in a protected manner, in which case sufficient cooling is simultaneously supplied through the opening and the adjacent cooler unit. The cooler unit arranged in the air flow of a propeller, which is driven by the rotational axis of the compressor, provides a cooling of the compressed air generated by the compressor before this compressed air is supplied to the pneumatic system. Simultaneously, the compressor itself is cooled by the air flow over its surface.

[0012] According to a measure improving this cooling effect, the air flow can be additionally intensified for the cooling of the compressor by the suction effect of a discharge device arranged above the compressor, so that the air flows, in a chimney-type manner, along the compressor for the cooling.

[0013] The fastening of the compressor on the vehicle floor preferably takes place by way of elastic bearing elements. As a result, an additional vibration decoupling is achieved between the vehicle floor and the compressor. A wire cable spring element or a rubber element, for example, are suitable for a use as the elastic bearing element. The elastic bearing elements may be arranged, on the one hand, between the housing of the compressor itself and the vehicle floor. On the other hand, it is conceivable to arrange the elastic bearing elements between the face-side cooler unit of the compressor and the vehicle floor. In addition to the elastic bearing elements assigned to the vehicle floor, additional fastening elements may be provided which are placed laterally between the compressor and the vehicle wall. Instead of the vehicle wall, at least one vertical fastening carrier can be used for the laterally supporting fastening of the compressor. The fastening elements used here are preferably also constructed as elastic bearing elements.

[0014] In order to be able to carry out, in the case of the standing arrangement of the compressor inside the vehicle, the maintenance work required at the appropriate cycles comfortably from the side without demounting the entire compressor, the maintained components of the compressor—such as the air filters, compressor housing lids and terminal box for the electrical connection of the driving unit—are advantageously further developed to be laterally easily accessible.

[0015] As described above, the compressor consists essentially of a driving unit as well as of a compressor unit constructed in the manner of a piston compressor or of a screw-type compressor. Here, the rotational axis of the driving unit preferably extends parallel or coaxial with respect to the rotational axis of the compressor unit in order to form the main axis of rotation of the compressor in this manner.

[0016] Additional measures improving the invention are indicated in the dependent claims or are explained in detail in the following together with the description of a preferred embodiment according to the invention by means of the figures.

[0017]FIG. 1 is a perspective outside view of an oil-free compressor equipped with a multistage piston compressor in the installed position according to the invention; and

[0018]FIG. 2 is a lateral view of the compressor according to FIG. 1 in the installed condition in a rail vehicle.

[0019] The oil-free compressor 1 according to FIG. 1 consists essentially of a compressor unit 2 with a coaxially flanged-on driving unit 3. The driving unit 3 is constructed as an electric motor and is detachably fastened to the housing 4 of the compressor unit 2 by means of a screwed connection. The driving unit 3 causes the rotational movement of a crankshaft—not visible here—arranged in the housing 4, which rotational movement is converted to a stroke movement for pistons which are housed inside the pot-shaped cylinders 5 a to 5 e fastened on the housing 4 for generating compressed air. By means of the piston movement, air is taken in from the atmosphere by way of an inlet-side air filter 6 and is compressed. The thus generated compressed air passes through a cooler unit 7 with a propeller and will then be available to the pneumatic system of a vehicle by way of the connection 8. In this embodiment, the compressor unit 2 is constructed as a multi-stage piston compressor with a low-pressure stage and a high-pressure stage. Here, cylinders 5 a, 5 c, 5 d are assigned to the low-pressure stage; cylinders 5 b and 5 e pertain to the high-pressure stage. The cylinders 5 a to 5 e are arranged in an opposed manner on the housing 4 of the compressor unit 2. For fastening the compressor unit 2 with the flanged-on driving unit 3 to a vehicle, a total of six elastic bearing elements are provided, of which only bearing elements 9 a to 9 e are visible here.

[0020] According to FIG. 2, the fastening of the compressor 1 takes place in a standing manner on a vehicle floor 10, so that the main axis of rotation 13 of the compressor 1 is arranged exactly vertically with respect to the vehicle floor 10. Each bearing element 9 consists of two fastening parts 11 a and 11 b. One fastening part 11 a is assigned to the vehicle floor 10, whereas the oppositely arranged other fastening part 11 b is fastened on the compressor side on the cooler unit 7 by means of a screwed connection. The wire cable spring 12 arranged between the two fastening parts 11 a and 11 b consists of several windings extending in the shape of a helical line. As a result, it is possible to connect the compressor unit 2, together with the driving unit, additionally in a vibration-damping manner with the vehicle floor 10. So that the compressor unit 2 itself generates as few vibrations as possible, its pistons operate in an opposed manner, in which case a dynamic balancing takes place with respect to the moved masses. Sufficient air for the cooling of the cooler unit 7 is taken in by way of an opening 14 in the vehicle floor 10 leading to the outside.

[0021] In addition to the elastic bearing elements 9 d, 9 e assigned to the vehicle floor 10, additional bearing elements 9 a, 9 b are provided which are arranged laterally between the compressor 1 and the vehicle wall 15. The compressor 1 is constructed such that its maintained components are laterally easily accessible in order to be able to carry out, in the case of the standing arrangement inside the vehicle, required maintenance work from this operating side without a complete demounting of the compressor 1. Maintained components of this type are a housing lid 16 of the compressor unit 2, the air filter 6 and a terminal box 17 by means of which the electrical connection of the driving unit takes place.

[0022] With respect to its construction, the present invention is not limited to the above embodiment indicated only in a preferably manner. On the contrary, modifications thereof are also conceivable which, despite a different further development, fall under the scope of protection of the invention defined by the claims. Furthermore, the invention is, in particular, not limited to a construction of the compressor unit as a piston compressor. The advantages of the invention are also achieved by means of a compressor unit of a different type which may, for example, be constructed as a screw-type compressor. It is also possible to accommodate the compressor at least partially outside the vehicle if the essentially vertical alignment of the main axis of rotation is retained with respect to the vehicle floor. List of Reference Numbers 1 Compressor 2 compressor unit 3 driving unit 4 housing 5 piston 6 air filter 7 cooler 8 connection 9 bearing element 10 vehicle floor 11 fastening part 12 wire cable spring 13 main axis of rotation 14 opening 15 vehicle wall 16 housing lid 17 terminal box 

1. Arrangement of an oil-free compressor on a vehicle, particularly on a rail vehicle, for supplying compressed air to various pneumatic units assigned to the vehicle, characterized in that the main axis of rotation (13) of the compressor (1) is arranged essentially vertically with respect to the vehicle floor (10), the compressor (1) being fastened at least on the front side on the vehicle floor (10).
 2. Arrangement according to claim 1, characterized in that the compressor (1) is arranged in a standing manner on the vehicle floor (10) in the interior of the vehicle and, adjacent to the vehicle floor (10), has a cooler unit (7) on the front side, which cooler unit (7) interacts by way of at least one opening (14) in the vehicle floor (10) leading to the outside, for taking in cooling air.
 3. Arrangement according to claim 1 or 2, characterized in that the air for cooling the cooler unit (7) flows in a chimney-type manner along the compressor (1) as a result of the suction effect of a discharge device arranged above the compressor (1).
 4. Arrangement according to claim 1, characterized in that the fastening of the compressor (1) on the vehicle floor (10) takes place by means of several elastic bearing elements (9).
 5. Arrangement according to claim 4, characterized in that the elastic bearing elements (9) are arranged between the housing (4) of the compressor unit (2) and the vehicle floor (10).
 6. Arrangement according to claim 4, characterized in that the elastic bearing elements (9) are arranged between the cooler unit (7) and the vehicle floor (10).
 7. Arrangement of claim 4, characterized in that, in addition to the elastic bearing elements (9 c to 9 e) assigned to the vehicle floor (10), additional fastening elements (9 a and 9 b) are provided which are arranged laterally between the compressor (1) and a vehicle wall (15) or at least one vertical fastening carrier.
 8. Arrangement according to one of the preceding claims, characterized in that the compressor (1) has laterally accessible maintenance components in order to be able, in the case of the standing arrangement of the compressor (1) inside the vehicle, to carry out required maintenance work from the side without a demounting of the compressor (1).
 9. Arrangement according to one of the preceding claims, characterized in that the compressor (1) consists essentially of a driving unit (3) as well as of a compressor unit (2) constructed in the manner of a piston compressor or a screw-type compressor, the axis of rotation of the driving unit (3) extending parallel or coaxially with respect to the axis of rotation of the compressor unit (2), in order to form the main axis of rotation (13) of the compressor (1).
 10. Arrangement according to claim 9, characterized in that, when the compressor unit (2) is constructed as a piston compressor, several individual cylinders (5 a to 5 e) are arranged in an opposed manner on the housing (4), so that the pistons situated in the cylinders (5 a to 5 e) move in a plane.
 11. Arrangement according to one of the preceding claims, characterized in that the fastening of the compressor (1) on the vehicle floor (10) takes place by way of a fastening carrier arranged in-between. 